Add Julia packages

[Culter]

I'm not an expert, but Oscar.jl and Symbolics.jl probably ought to be listed:

• https://www.oscar-system.org/about/
• https://symbolics.juliasymbolics.org/stable/

For a single-slide comparison of the two, see https://youtu.be/rWQK4mU3jQc?t=446